1. Field of the Invention
This invention relates to industrial tools, and particularly to a bit having carbide tips mounted at an angle for scarifying concrete.
2. Description of the Prior Art
It is believed the prior art related to this invention may be found in the following classes and sub-classes:
Class 125, sub-classes 6, 7, 40, 41
Class 299, sub-class 94
Class 175, sub-class 395
Class 173, sub-class 94
Class 404, sub-class 90
Class 30, sub-class 168
A search of the classes and sub-classes indicated above revealed the existence of U.S. Pat. Nos. 1,252,082; 1,995,060; 2,752,141; 3,403,443; and 3,675,973.
U.S. Pat. No. 1,252,082 discloses a cutting tool that utilizes four bits, each being square in cross section and having a pyramidal end. When the four bits are clustered together, the four pyramidal points form the cutting end of the tool. When the apex of the pyramid formed by each bit is worn down, the bits are re-sharpened on the outside surface and eventually rotated so as to expose a new surface. When the bits have been worn down from repeated use and repeated sharpening, then the bits are loosened in their holder and each is revolved through 180.degree. so as to place the long bevel as it appears in FIG. 9 of the patent on the outside of the bit, into the position illustrated in FIG. 10 on the inside of the bit.
U.S. Pat. No. 1,995,060 relates to a stone channeling bit that utilizes a multiplicity of separate chisel points removably secured on the end of a holder.
U.S. Pat. No. 2,752,141 is directed to a structure adapted to be mounted on the front of a truck for the purpose of pulverizing pavement. The tool or bit 54 which does the pulverizing constitutes a truncated three-sided pyramid. The upper edges 58 and the lower edge 60 of the bit are disposed in mutually convergent relation, terminating at the smaller triangular front face 62 of the tool so that the lower edge 60 presents an upwardly inclined cutting surface.
U.S. Pat. No. 3,403,443 relates to a drill bit for shattering hard formations such as concrete. This tool is not used for scarifying but rather for the complete destruction of a hard formation such as concrete, and is provided with wedges 5 which follow the bit into the concrete to enlarge the opening formed by the bit.
U.S. Pat. No. 3,675,973 relates to a concrete breaker tool the working surface of which is provided with three hexagonal breaking bars or points 20, 21 and 22. The inventive concept of this patent appears to be that the center hexagonal breaking bar 21 is longer than the breaking bars 20 and 22, thus penetrating the concrete surface first. Penetration of the center breaker bar first is alleged to weaken the concrete on opposite sides, with the two side breaker bars 20 and 22 thus encountering a weakened surface to effectively break the concrete.
As is well known, concrete constitutes a mixture of Portland cement and aggregate, the aggregate including various sized pebbles and a quantity of sand. With the addition of water, a thick plastic mass is formed which with time hardens into concrete as we know it and see it in use for pavements and for construction of various types. For many different reasons, a layer of concrete frequently develops cracks. Sometimes cracks may form because of temperature cycling and differential rates of expansion and contraction between the concrete and adjacent structures. At other times, the concrete will crack because of externally imposed forces such as the pressure exerted by a root from an adjacent tree.
Whatever the reasons, such cracks permit the passage of water into the sub-base below the concrete and in some instances result in unevenness of paving, causing a sharp declevity, with the result that it provides a sharp edge over which an unsuspecting person might trip and fall and sustain physical injury, thus imposing liability on the owner of the concrete paving. Wherever such cracks occur, it is advantageous that they be repaired expeditiously and at low cost. Heretofore, an entire section or square of a concrete sidewalk had to be removed in order to repair such a crack. Accordingly, it is one of the objects of the present invention to provide a scarifier tool that may be applied to the concrete surface in close association to the crack to roughen such surface and to open the crack sufficiently to permit the application of a sealing compound to the surface of the concrete and a filler material in the crack, thus sealing the crack therein.
It sometimes happens that entire concrete surfaces are formed in such a way that they are exceedingly slippery when wet or when covered with other type liquids. In such instances, it is an advantage to roughen the entire surface either for purposes of increasing the traction on the surface by wheeled vehicles or by pedestrians, or for the purpose of applying a different type of coating on the concrete surface. For instance, it is well known that concrete formed from Portland cement and aggregate is not resistant to the effects of blood, such as in slaughter houses and butcher shops, and that epoxy concrete in which the binder constitutes a synthetic epoxy rather than Portland cement is much more resistant to the chemical effects of blood and other caustic chemicals. However, epoxy concrete cannot be applied over a smooth surface of Portland cement concrete without "scarifying" the surface of the Portland cement concrete to roughen the surface and provide an adequate mechanical bonding surface for the application of epoxy concrete. Accordingly, another object of the invention is the provision of a tool which may be mounted in a reciprocating and/or rotatable drive mechanism and which, when directed to the surface of Portland cement concrete, will effect a disintegration of the smooth top surface so as to expose the underlying rough aggregate without causing cracks in the main body of the concrete.
Conventional tools used for the purpose of scarifying concrete constitute a head that is reciprocable by some appropriate driving mechanism, the head being provided with a longitudinal axis along which it reciprocates, and with a plurality of axially extending carbide tips that are embedded in the head with the longitudinal axes of the carbide tips parallel to the longitudinal axis of the reciprocable head. Frequently, the elongated carbide tips are shaped on their exposed end into a cone-form so that the sharpened ends of the carbide tips bite into the concrete when applied thereto. It has been found that after only a few hours of use of such a conventional head to concrete, the cone-shaped carbide tips wear away, exposing a rounded end that is much less efficient for scarifying concrete than the original point. Obviously, as the conventional tool is continued to be used, the end of the carbide tip becomes worn to a greater degree, thus decreasing the efficiency of the operation as it progresses.
Accordingly, another object of the present invention is the provision of a tool in which the carbide tips are embedded in the head structure in such a way that a multiplicity of sharp edges are exposed to the concrete, thus increasing the efficiency of operation of the head when used for scarifying concrete.
Another object of the invention is the provision of a scarifying tool provided with carbide tip cutting members embedded in the head in such a way that the head may be reprocessed to utilize the same carbide tips in the same head but with different edges of the carbide tips exposed so as to lengthen the life of the tool and thus economize through the use of carbide cutting members for many more hours than is usually the case.
Another object of the invention is the provision of a tool that may be applied to conventional drive units, the tool including a head in which a multiplicity of carbide tips are embedded in a special way, and a shank having an internal bore adapted to receive the reciprocable shaft of a driving mechanism, with means being applied between the tool and the driving mechanism to retain the head on the reciprocable shaft during use.
The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawings. It is to be understood, however, that the invention is not limited to the embodiment illustrated and described, since it may be embodied in various forms within the scope of the appended claims.